Single-grain near-field transducer and process for forming same
A method involves forming a metal layer on a metal seed layer, the metal seed layer formed on a carrier wafer. A surface of the metal layer defines a first metal bonding layer. A second metal bonding layer is provided on a target substrate having recording head subassemblies. Mating surfaces of the first and second metal bonding layers are activated and the carrier wafer is flipped and joined with the target substrate such that the first and second metal bonding layers are bonded and the metal layer is integrated with the recording head as a near-field transducer.
1. A method comprising:
forming a metal layer on a metal seed layer, the metal layer comprising a platinum group metal and having a structure with either no grain boundaries or coherent grain boundaries only, the metal seed layer formed on a carrier wafer, wherein the metal layer is formed with a predetermined crystalline orientation relative to the carrier wafer and a surface of the metal layer defines a first metal bonding layer;
providing a second metal bonding layer on a target substrate, the target substrate comprising one or more recording head subassemblies;
activating mating surfaces of the first and second metal bonding layers; and
flipping and joining the carrier wafer with the target substrate such that the first and second metal bonding layers are bonded and the metal layer is integrated with the recording head as a near-field transducer, wherein joining the carrier wafer with the target substrate comprises rotating the carrier wafer relative to the target substrate to provide in-plane orientation control of the near-field transducer relative to an air-bearing surface of the recording head.
2. The method of claim 1 , wherein providing the second metal bonding layer comprises forming the second metal bonding layer on the target substrate.
3. The method of claim 1 , wherein native metal on a surface of the target substrate defines the second metal bonding layer.
4. The method of claim 1 , further comprising patterning the metal layer into a target shape, the target shape defining a shape of the near-field transducer or a shape larger than the near-field transducer shape.
5. The method of claim 4 , wherein patterning the metal layer comprises etching or milling to the target shape.
6. The method of claim 4 , wherein patterning the metal layer comprises etching or milling to a target thickness.
7. The method of claim 4 , wherein patterning the metal layer comprises planarizing to a target thickness.
8. The method of claim 1 , wherein the platinum group metal comprises at least one of Rh, Pd, Ir, Pt, or an alloy thereof.
9. The method of claim 1 , wherein the bonding of the first and second metal bonding layers forms a direct metal-metal bond without a diffusion layer in between.
10. The method of claim 1 , wherein activating the mating surfaces of the first and second metal bonding layers comprises using plasma or ion beam of at least one of Ar, O 2 , N 2 , Ne, Xe, He, and Kr.
11. The method of claim 1 , wherein rotating the carrier wafer relative to the target substrate to provide in-plane orientation control of the near-field transducer relative to the air-bearing surface (ABS) results in a crystal orientation of an ABS-facing edge of the near-field transducer having a high atomic packing factor.
12. The method of claim 11 , wherein the platinum group metal comprises a face centered cubic metal, and wherein the crystal orientation comprises ( 100 ) or ( 111 ).
13. The method of claim 1 , wherein the second metal bonding layer comprises a second platinum group metal.
14. The method of claim 13 , wherein the second platinum group metal comprises at least one of Rh, Pd, Ir, Pt, or an alloy thereof.
15. The method of claim 1 , wherein the second platinum group metal is the same as the platinum group metal of the metal layer.
16. The method of claim 1 , wherein the wherein the second metal bonding layer comprises at least one of Au, Ag, Cu, Al, or an alloy thereof.
17. The method of claim 1 , wherein the carrier wafer comprises an epitaxial template for the metal seed layer.
18. The method of claim 17 , wherein the carrier wafer comprises one of Si, sapphire, NaCl, MgO, SrTiO3, and Yttrium stabilized zirconia.
19. An apparatus comprising the recording head of claim 1 , the recording head formed using the method of claim 1 .